Syndesmosis Injury: Understanding the High Ankle Sprain
A syndesmosis injury, often referred to as a high ankle sprain, is quite different from the more familiar ankle sprain that occurs around the outside of the ankle.
While both injuries involve ligaments around the ankle, they affect different structures, usually occur through different mechanisms and can require very different rehabilitation. Syndesmosis injuries can also take longer to recover from, particularly when the injury affects the stability between the two bones of the lower leg.
They are commonly seen in field and court sports where athletes are exposed to tackling, twisting, awkward landings and rapid changes of direction. If you have injured your ankle during sport, our Sports Physiotherapy team can help determine which structures are involved and guide your rehabilitation back to running, training and competition.
What Is the Syndesmosis?
The syndesmosis is the group of strong connective tissues that joins the tibia and fibula, the two bones of the lower leg, just above the ankle joint.
The main structures of the syndesmosis include:
- Anterior inferior tibiofibular ligament (AITFL), which sits across the front of the tibia and fibula.
- Posterior inferior tibiofibular ligament (PITFL), which supports the back of the joint.
- Interosseous ligament and interosseous membrane, which provide additional stability between the two lower-leg bones.
Together, these structures help maintain the relationship between the tibia and fibula as the ankle moves and accepts load.
This relationship needs to remain relatively precise during activities such as walking, running, jumping and changing direction. When the syndesmosis is injured, loading the ankle can become painful and, in more significant injuries, the stability of the ankle joint itself can be compromised.
How Does a High Ankle Sprain Happen?
A common mechanism for a syndesmosis injury occurs when the foot is forced upwards into dorsiflexion while also rotating outwards relative to the lower leg.
This external rotation force can place considerable stress through the tissues connecting the tibia and fibula.
In sport, this might occur when:
- The foot is planted while the body rotates over the ankle.
- An athlete is tackled while their foot remains trapped underneath them.
- Another player falls across the outside of the leg.
- The ankle is forced into an awkward position during landing.
- A large twisting force occurs while the athlete is weight-bearing.
Not every syndesmosis injury occurs in exactly the same way. Depending on the mechanism, other structures within the foot and ankle may also be injured at the same time.
What Does a Syndesmosis Injury Feel Like?
The symptoms of a high ankle sprain vary considerably depending on the severity of the injury.
One common feature is pain slightly higher than the typical lateral ankle sprain. Rather than pain sitting directly underneath or around the outside ankle bone, discomfort is often felt at the front of the ankle or slightly above the ankle joint between the tibia and fibula.
Symptoms can include:
- Pain when walking or pushing through the foot.
- Pain above or across the front of the ankle.
- Difficulty running.
- Pain with twisting, pivoting or changing direction.
- Tenderness between the tibia and fibula.
- Swelling around or above the ankle joint.
- Reduced ankle movement.
- Difficulty hopping, jumping or landing.
- A feeling that the ankle is uncomfortable or unstable under load.
Some syndesmosis injuries are immediately obvious. Others can initially appear to be relatively minor ankle sprains before becoming more problematic when someone attempts to progress back to running or sport.
How Is a High Ankle Sprain Different From a Normal Ankle Sprain?
The traditional ankle sprain most people are familiar with usually involves the ligaments on the outside of the ankle, particularly the anterior talofibular ligament (ATFL).
A syndesmosis injury occurs higher up and involves the structures connecting the tibia and fibula.
This distinction matters because the two injuries can behave quite differently.
A mild lateral ankle sprain may sometimes improve relatively quickly once swelling settles and movement, strength and confidence return. Syndesmosis injuries often require greater consideration of how much load the ankle can tolerate and, importantly, whether the relationship between the tibia and fibula remains stable.
This is one reason why a significant high ankle sprain should not simply be treated in the same way as a standard rolled ankle.
You can learn more about how we assess and manage ankle injuries on our Foot & Ankle Physiotherapy page.
How Is a Syndesmosis Injury Diagnosed?
Assessment usually starts with understanding exactly how the injury occurred.
The mechanism can provide valuable information about which structures may have been placed under stress.
A physiotherapy assessment will then usually consider:
- Where the pain and tenderness are located.
- The degree and location of swelling.
- Ankle range of movement.
- Ability to stand and walk.
- Pain with loading the ankle.
- A series of clinical tests designed to assess the syndesmosis.
- The possibility of injury to other ligaments, bones or structures around the ankle.
It is also important not to assess the syndesmosis in isolation. Some high ankle sprains occur alongside fractures, deltoid ligament injuries or other injuries around the ankle and lower leg.
Do You Need an X-Ray or MRI?
Imaging is not required for every ankle injury.
Depending on the mechanism of injury and findings during assessment, an X-ray may be appropriate to investigate the possibility of a fracture or significant separation between the tibia and fibula.
An MRI can provide more detailed information about the syndesmosis ligaments and other soft tissues when this is clinically useful.
Where there is concern about instability or a more substantial syndesmosis injury, further medical, radiological or orthopaedic assessment may also be recommended.
How Are Syndesmosis Injuries Treated?
Treatment depends on the severity of the injury and, importantly, whether the ankle remains stable.
A stable syndesmosis injury can usually be managed without surgery.
During the early stages of rehabilitation, the aim is generally to reduce unnecessary stress through the injured tissues while still maintaining as much safe movement and activity as possible.
Depending on the injury, this may include temporary use of:
- A moon boot.
- An ankle brace.
- Crutches.
- Modified weight-bearing.
- Temporary modification of training and sporting activity.
The amount of protection required can vary substantially from one person to another. Some people need only a short period of reduced loading, whereas more significant injuries may require considerably more protection before rehabilitation progresses.
What Does Syndesmosis Rehabilitation Involve?
Once the injury is ready to tolerate greater load, rehabilitation progressively rebuilds the ankle's capacity.
A rehabilitation program may include:
- Ankle mobility: Gradually restoring comfortable movement through the ankle joint.
- Calf strength: Rebuilding the capacity of the calf complex to absorb and generate force.
- Ankle and lower-leg strength: Improving control of the foot, ankle and lower limb.
- Balance and proprioception: Restoring the body's ability to control the ankle during standing and movement.
- Single-leg control: Progressing from basic balance through to demanding single-leg tasks.
- Hopping and landing: Gradually preparing the ankle to absorb higher forces.
- Running: Progressing from straight-line running towards higher speeds and greater volume.
- Acceleration and deceleration: Preparing the athlete for the demands of field and court sport.
- Change of direction: Reintroducing cutting, pivoting and reactive movements.
- Sport-specific rehabilitation: Building towards the movements and workloads required during training and competition.
The goal is not simply to wait until the ankle stops hurting. Rehabilitation should progressively prepare the ankle for the forces it will experience when you return to running, training and sport.
Our Sports Physiotherapy approach focuses on restoring the physical qualities required for your sport rather than relying on time alone.
When Does a Syndesmosis Injury Need Surgery?
Not every significant syndesmosis injury requires surgery.
The key consideration is often stability.
If the injury has resulted in significant separation or instability between the tibia and fibula, surgical stabilisation may be required to restore the normal relationship between these bones.
These injuries are important to identify early.
An unstable syndesmosis that continues to be repeatedly loaded can behave very differently from a stable ligament injury that can safely progress through rehabilitation.
How Long Does a High Ankle Sprain Take to Recover?
There is no single recovery time that applies to every syndesmosis injury.
A relatively minor, stable injury can progress considerably faster than an injury involving multiple syndesmosis structures or instability. Injuries requiring surgery generally involve a longer rehabilitation process again.
Return to sport should therefore be based on more than simply counting the number of weeks since the injury.
Before returning to unrestricted sport, we generally want to see progression towards:
- Comfortable walking and normal daily activity.
- Adequate ankle range of movement.
- Restoration of calf and lower-limb strength.
- Good single-leg balance and control.
- Tolerance of hopping and landing.
- Well-tolerated running at appropriate speeds.
- Acceleration and deceleration capacity.
- Change-of-direction ability.
- Confidence during sport-specific movements.
For athletes, additional strength, jump, hop and movement testing may also help determine whether the ankle is ready for the demands of training and competition.
Have You Injured Your Ankle?
An ankle injury does not automatically mean that you have injured the syndesmosis.
However, pain above the ankle, difficulty walking, a significant twisting mechanism or persistent difficulty returning to running are all good reasons to have the injury properly assessed.
Identifying which structures are involved helps determine whether the ankle can begin loading relatively quickly or whether the injury requires greater protection, imaging or further investigation.
Our physiotherapists assess and rehabilitate ankle injuries ranging from everyday ankle sprains through to more significant sporting injuries and return-to-sport rehabilitation.
Learn more about our Foot & Ankle Physiotherapy services or our approach to Sports Physiotherapy.
